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Message-ID: <20151022153756-mutt-send-email-mst@redhat.com>
Date: Thu, 22 Oct 2015 15:40:27 +0300
From: "Michael S. Tsirkin" <mst@...hat.com>
To: Lan Tianyu <tianyu.lan@...el.com>
Cc: bhelgaas@...gle.com, carolyn.wyborny@...el.com,
donald.c.skidmore@...el.com, eddie.dong@...el.com,
nrupal.jani@...el.com, yang.z.zhang@...el.com, agraf@...e.de,
kvm@...r.kernel.org, pbonzini@...hat.com, qemu-devel@...gnu.org,
emil.s.tantilov@...el.com, intel-wired-lan@...ts.osuosl.org,
jeffrey.t.kirsher@...el.com, jesse.brandeburg@...el.com,
john.ronciak@...el.com, linux-kernel@...r.kernel.org,
linux-pci@...r.kernel.org, matthew.vick@...el.com,
mitch.a.williams@...el.com, netdev@...r.kernel.org,
shannon.nelson@...el.com
Subject: Re: [RFC Patch 10/12] IXGBEVF: Add lock to protect tx/rx ring
operation
On Thu, Oct 22, 2015 at 12:37:42AM +0800, Lan Tianyu wrote:
> Ring shifting during restoring VF function maybe race with original
> ring operation(transmit/receive package). This patch is to add tx/rx
> lock to protect ring related data.
>
> Signed-off-by: Lan Tianyu <tianyu.lan@...el.com>
That's adding a bunch of locking on data path - what's the
performance impact?
Can't you do something faster? E.g. migration things
are slow path - can't you use something like RCU
to flush outstanding work?
> ---
> drivers/net/ethernet/intel/ixgbevf/ixgbevf.h | 2 ++
> drivers/net/ethernet/intel/ixgbevf/ixgbevf_main.c | 28 ++++++++++++++++++++---
> 2 files changed, 27 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/net/ethernet/intel/ixgbevf/ixgbevf.h b/drivers/net/ethernet/intel/ixgbevf/ixgbevf.h
> index 6eab402e..3a748c8 100644
> --- a/drivers/net/ethernet/intel/ixgbevf/ixgbevf.h
> +++ b/drivers/net/ethernet/intel/ixgbevf/ixgbevf.h
> @@ -448,6 +448,8 @@ struct ixgbevf_adapter {
>
> spinlock_t mbx_lock;
> unsigned long last_reset;
> + spinlock_t mg_rx_lock;
> + spinlock_t mg_tx_lock;
> };
>
> enum ixbgevf_state_t {
> diff --git a/drivers/net/ethernet/intel/ixgbevf/ixgbevf_main.c b/drivers/net/ethernet/intel/ixgbevf/ixgbevf_main.c
> index 15ec361..04b6ce7 100644
> --- a/drivers/net/ethernet/intel/ixgbevf/ixgbevf_main.c
> +++ b/drivers/net/ethernet/intel/ixgbevf/ixgbevf_main.c
> @@ -227,8 +227,10 @@ static u64 ixgbevf_get_tx_completed(struct ixgbevf_ring *ring)
>
> int ixgbevf_tx_ring_shift(struct ixgbevf_ring *r, u32 head)
> {
> + struct ixgbevf_adapter *adapter = netdev_priv(r->netdev);
> struct ixgbevf_tx_buffer *tx_buffer = NULL;
> static union ixgbevf_desc *tx_desc = NULL;
> + unsigned long flags;
>
> tx_buffer = vmalloc(sizeof(struct ixgbevf_tx_buffer) * (r->count));
> if (!tx_buffer)
> @@ -238,6 +240,7 @@ int ixgbevf_tx_ring_shift(struct ixgbevf_ring *r, u32 head)
> if (!tx_desc)
> return -ENOMEM;
>
> + spin_lock_irqsave(&adapter->mg_tx_lock, flags);
> memcpy(tx_desc, r->desc, sizeof(union ixgbevf_desc) * r->count);
> memcpy(r->desc, &tx_desc[head], sizeof(union ixgbevf_desc) * (r->count - head));
> memcpy(&r->desc[r->count - head], tx_desc, sizeof(union ixgbevf_desc) * head);
> @@ -256,6 +259,8 @@ int ixgbevf_tx_ring_shift(struct ixgbevf_ring *r, u32 head)
> else
> r->next_to_use += (r->count - head);
>
> + spin_unlock_irqrestore(&adapter->mg_tx_lock, flags);
> +
> vfree(tx_buffer);
> vfree(tx_desc);
> return 0;
> @@ -263,8 +268,10 @@ int ixgbevf_tx_ring_shift(struct ixgbevf_ring *r, u32 head)
>
> int ixgbevf_rx_ring_shift(struct ixgbevf_ring *r, u32 head)
> {
> + struct ixgbevf_adapter *adapter = netdev_priv(r->netdev);
> struct ixgbevf_rx_buffer *rx_buffer = NULL;
> static union ixgbevf_desc *rx_desc = NULL;
> + unsigned long flags;
>
> rx_buffer = vmalloc(sizeof(struct ixgbevf_rx_buffer) * (r->count));
> if (!rx_buffer)
> @@ -274,6 +281,7 @@ int ixgbevf_rx_ring_shift(struct ixgbevf_ring *r, u32 head)
> if (!rx_desc)
> return -ENOMEM;
>
> + spin_lock_irqsave(&adapter->mg_rx_lock, flags);
> memcpy(rx_desc, r->desc, sizeof(union ixgbevf_desc) * (r->count));
> memcpy(r->desc, &rx_desc[head], sizeof(union ixgbevf_desc) * (r->count - head));
> memcpy(&r->desc[r->count - head], rx_desc, sizeof(union ixgbevf_desc) * head);
> @@ -291,6 +299,7 @@ int ixgbevf_rx_ring_shift(struct ixgbevf_ring *r, u32 head)
> r->next_to_use -= head;
> else
> r->next_to_use += (r->count - head);
> + spin_unlock_irqrestore(&adapter->mg_rx_lock, flags);
>
> vfree(rx_buffer);
> vfree(rx_desc);
> @@ -377,6 +386,8 @@ static bool ixgbevf_clean_tx_irq(struct ixgbevf_q_vector *q_vector,
> if (test_bit(__IXGBEVF_DOWN, &adapter->state))
> return true;
>
> + spin_lock(&adapter->mg_tx_lock);
> + i = tx_ring->next_to_clean;
> tx_buffer = &tx_ring->tx_buffer_info[i];
> tx_desc = IXGBEVF_TX_DESC(tx_ring, i);
> i -= tx_ring->count;
> @@ -471,6 +482,8 @@ static bool ixgbevf_clean_tx_irq(struct ixgbevf_q_vector *q_vector,
> q_vector->tx.total_bytes += total_bytes;
> q_vector->tx.total_packets += total_packets;
>
> + spin_unlock(&adapter->mg_tx_lock);
> +
> if (check_for_tx_hang(tx_ring) && ixgbevf_check_tx_hang(tx_ring)) {
> struct ixgbe_hw *hw = &adapter->hw;
> union ixgbe_adv_tx_desc *eop_desc;
> @@ -999,10 +1012,12 @@ static int ixgbevf_clean_rx_irq(struct ixgbevf_q_vector *q_vector,
> struct ixgbevf_ring *rx_ring,
> int budget)
> {
> + struct ixgbevf_adapter *adapter = netdev_priv(rx_ring->netdev);
> unsigned int total_rx_bytes = 0, total_rx_packets = 0;
> u16 cleaned_count = ixgbevf_desc_unused(rx_ring);
> struct sk_buff *skb = rx_ring->skb;
>
> + spin_lock(&adapter->mg_rx_lock);
> while (likely(total_rx_packets < budget)) {
> union ixgbe_adv_rx_desc *rx_desc;
>
> @@ -1078,6 +1093,7 @@ static int ixgbevf_clean_rx_irq(struct ixgbevf_q_vector *q_vector,
> q_vector->rx.total_packets += total_rx_packets;
> q_vector->rx.total_bytes += total_rx_bytes;
>
> + spin_unlock(&adapter->mg_rx_lock);
> return total_rx_packets;
> }
>
> @@ -3572,14 +3588,17 @@ static void ixgbevf_tx_map(struct ixgbevf_ring *tx_ring,
> struct ixgbevf_tx_buffer *tx_buffer;
> union ixgbe_adv_tx_desc *tx_desc;
> struct skb_frag_struct *frag = &skb_shinfo(skb)->frags[0];
> + struct ixgbevf_adapter *adapter = netdev_priv(tx_ring->netdev);
> unsigned int data_len = skb->data_len;
> unsigned int size = skb_headlen(skb);
> unsigned int paylen = skb->len - hdr_len;
> + unsigned long flags;
> u32 tx_flags = first->tx_flags;
> __le32 cmd_type;
> - u16 i = tx_ring->next_to_use;
> - u16 start;
> + u16 i, start;
>
> + spin_lock_irqsave(&adapter->mg_tx_lock, flags);
> + i = tx_ring->next_to_use;
> tx_desc = IXGBEVF_TX_DESC(tx_ring, i);
>
> ixgbevf_tx_olinfo_status(tx_desc, tx_flags, paylen);
> @@ -3673,7 +3692,7 @@ static void ixgbevf_tx_map(struct ixgbevf_ring *tx_ring,
>
> /* notify HW of packet */
> ixgbevf_write_tail(tx_ring, i);
> -
> + spin_unlock_irqrestore(&adapter->mg_tx_lock, flags);
> return;
> dma_error:
> dev_err(tx_ring->dev, "TX DMA map failed\n");
> @@ -3690,6 +3709,7 @@ dma_error:
> }
>
> tx_ring->next_to_use = i;
> + spin_unlock_irqrestore(&adapter->mg_tx_lock, flags);
> }
>
> static int __ixgbevf_maybe_stop_tx(struct ixgbevf_ring *tx_ring, int size)
> @@ -4188,6 +4208,8 @@ static int ixgbevf_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
> break;
> }
>
> + spin_lock_init(&adapter->mg_tx_lock);
> + spin_lock_init(&adapter->mg_rx_lock);
> return 0;
>
> err_register:
> --
> 1.8.4.rc0.1.g8f6a3e5.dirty
>
> --
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